The present invention relates generally to the field of hydraulic circuits within an automatic transmission and, more particularly, to a Torque Converter Clutch (hereinafter xe2x80x9cTCCxe2x80x9d) Apply Valve for General Motors 4T60-E and other similar transmissions that directs torque converter fluid pressure to the TCC apply and release circuits to actuate the torque converter clutch.
Automatic transmission systems of the prior art have a hydraulic circuit subsystem which includes at least a hydraulic pump, a valve body having fluid conducting passageways or circuits, input and exhaust ports formed within the fluid circuits, and a plurality of xe2x80x9cspoolxe2x80x9d valves so-called because of their resemblance to sewing thread spools. Such spool valves are comprised of modified, cylindrical pistons which alternately open and close fluid ports within the valve body to regulate the flow and pressure of automatic transmission fluid (hereinafter xe2x80x9cATFxe2x80x9d) within the fluid circuits to actuate different components of the transmission. It will be understood that in describing hydraulic fluid circuits, ATF usually changes names when it passes through an orifice or control valve in a specific circuit.
ATF leakage within the TCC apply and release circuits occurs due to the constant oscillation and abrasive action of the steel TCC apply valve within the mating bore of the aluminum valve body, which results in a loss of converter apply pressure. The loss of pressure in the apply circuit causes TCC slippage, converter shudder, and eventually an overheated and/or burned torque converter. Thus, the present invention has been developed to resolve these problems and other shortcomings of the prior art.
Accordingly, the present invention provides a replacement TCC Apply Valve including an apply valve piston having an expandable seal fabricated from polytetrafluoroethylene (hereinafter xe2x80x9cPTFExe2x80x9d) i.e. Teflon(copyright) or other similar material installed thereon at the primary wear location within the valve body to reduce ATF leakage. The present valve piston also includes an internal ATF gallery with radially extending passages formed therein in fluid communication with an annular groove wherein the expandable seal resides. Whenever the present TCC Apply Valve is actuated by the TCC solenoid, TCC signal pressure forces ATF into the gallery in the apply valve piston and further urges the seal radially outward into contact with the bore to minimize ATF leakage during the apply cycle of the torque converter clutch.
There has thus been outlined, rather broadly, the important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto.
Those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.